There are many applications where there is a need for a high gas barrier in a flexible film such as in food packaging, silage wrap, stretch hooder applications, and as a radon barrier for residential construction. Films made with ethylene vinyl alcohol (EVOH) polymers are known to be excellent barriers with respect to oxygen and other gases, but EVOH is a brittle polymer with a tendency to crack under simple bending or with an elongation of more than 20%. Once the EVOH layer is cracked the film's barrier properties are significantly degraded. What is needed is a way to modify the EVOH to enable it to withstand nominal abuse conditions without significant decrease in oxygen barrier properties.
In the present invention it was found that by the addition of an ultra-low molecular weight, ultra low density, anhydride and/or carboxylic acid functionalized ethylene/alpha-olefin interpolymer into the EVOH matrix that the EVOH layer will demonstrate significantly improved elongation properties and abuse resistance without significantly altering the pure material's barrier properties.
Accordingly, the present invention relates to a film comprising at least one barrier layer, said barrier layer comprising at least 5 percent, by weight of the layer, of an anhydride and/or carboxylic acid functionalized ethylene/alpha-olefin interpolymer having a density in the range of from 0.855 to 0.900 g/cm3; and having a melt index (190° C./2.16 kg) of greater than 200 g/10 min. The barrier film further comprises at least 60 percent, by weight of the layer, of an EVOH polymer.